There are Documents on stabilization of a compound that contains arsenic.
Patent Document 1 describes a method of producing scorodite directed to arsenic that is contained in smelter soot.
Patent Document 2 relates to a method of leaching arsenic sulfide. It describes adding alkali while blowing air to slurry that contains arsenic sulfide, and leaching arsenic while maintaining the pH to 5 to 8.
Non-Patent Document 1 reports solubility products of iron arsenate, calcium arsenate and magnesium arsenate. According to the document, while calcium arsenate and magnesium arsenate are stable only in an alkali region, iron arsenate is stable in a neutral to acidic region. The document reports the minimum solubility 20 mg/l at pH 3.2.
Non-Patent Document 2 discloses solubility of iron arsenate and scorodite. The literature indicates that solubility of arsenic from scorodite in a weak acidic region is lower than solubility of arsenic from amorphous iron arsenate by two digits, which discloses that scorodite is a stable arsenic compound.
Non-Patent Document 3 describes a method of producing scorodite directed to arsenic that is contained in wastewater from sulfuric acid plants or smelters.
[Patent document 1] Japanese Patent Application Laid Open No. 2005-161123
[Patent document 2] Japanese Patent Publication No. 61-24329
[Non-patent document 1] Tadahisa Nishimura, Kazumitsu Tozawa, “Report of Research Institute of Mineral Dressing and Metallurgy, Tohoku University” No. 764, Vol. 34, Separate Print No. 1, 1978, June
[Non-patent document 2] E. Krause and V. A. Ettel, “Solubilities and Stabilities of Ferric Arsenate Compounds” Hydrometallurgy, 22, 311-337, (1989)
[Non-patent document 3] Dimitrios Filippou and George P. Demopoulos, “Arsenic Immobilization by Cotrolled Scorodite Precipitation” JOM Dec., 52-55, (1997)